Add KeepAlive option for Azure-arm-rest (#318)

- Since node19 http.GlobalAgent has timeout for 5 sec which might be too short for Azure REST API
  By addeding keppALive request option we construct own agent with longer timeout
  Ref doc: https://nodejs.org/docs/latest/api/http.html#httpglobalagent

Author: DmitriiBobreshev

common-npm-packages/azure-arm-rest/package-lock.json

@@ -25,7 +25,7 @@
     "jsonwebtoken": "^8.5.1",
     "node-fetch": "^2.6.7",
     "q": "1.5.1",
-    "typed-rest-client": "1.8.4",
+    "typed-rest-client": "^1.8.6",
     "xml2js": "0.6.2"
   },
   "devDependencies": {

common-npm-packages/azure-arm-rest/package.json

@@ -13,7 +13,8 @@ var requestOptions: httpInterfaces.IRequestOptions = proxyUrl ? {
         proxyBypassHosts: tl.getVariable("agent.proxybypasslist") ? JSON.parse(tl.getVariable("agent.proxybypasslist")) : null
     }
 } : {
-    allowRedirects: false
+    allowRedirects: false,
+    keepAlive: true
 };
 
 let ignoreSslErrors: string = tl.getVariable("VSTS_ARM_REST_IGNORE_SSL_ERRORS");